The proposed research would be a joint effort with the Yale University School of Medicine (Dr. Evans) to evaluate the part played by EBV and other common viral infections in the pathogenesis of systemic lupus erythematosus (SLE), rheumatoid arthritis and other connective tissue diseases. Tests for antinuclear antibodies would be made on single and serial samples from patients with systemic lupus erythematosus and from patients receiving drugs which have been shown to induce antinuclear antibodies and clinical systemic lupus erythematosus. A battery of viral antibody tests would be performed on serial samples from these patients as well as on sera from patients with rheumatoid arthritis and other connective tissue diseases, and from relatives of patients with systemic lupus erythematosus.